Steric effects on binding O2, SO2 and CH3I to square-planar iridium(I) complexes, trans-Ir(CO)(Cl)(P(i-Pr)3)2 and trans-Ir(CO)(Cl)(P(t-Bu)2Me)2

Steric and electronic effects of phosphine ligands on binding of molecules to iridium(I) have been probed by studying reactions of O-2, SO2 and CH3I with trans-Ir(CO)(Cl)(P(i-Pr)(3))(2) and trans-Ir(CO)(Cl)(P(t-Bu)(2)Me)(2) for comparison to known reactions with trans-Ir(CO)(Cl)L-2 (L = PPh3, P(p-tolyl)(3) and PCy3). Reaction of O-2 is significantly retarded by increasing size of the ligand while reaction of SO2 is essentially unaffected by the nature of the phosphine ligand. Reaction of CH3I with trans-Ir(CO)(Cl)(P(t-Bu)(2)Me)(2) produces two products which have been characterized by NMR and infrared spectroscopy.